How many electrons can fit in the third energy level (n=3) of an atom?

The third energy level, indicated by the principal quantum number ( n = 3 ), can hold a maximum number of electrons determined by the formula ( 2n^2 ). By substituting ( n = 3 ) into the formula, you calculate:

[

2n^2 = 2(3^2) = 2(9) = 18

]

This means that the third energy level can accommodate a total of 18 electrons. Electrons fill the energy levels based on specific rules, and the third energy level includes the subshells ( s ), ( p ), and ( d ). More specifically:

• The 3s subshell can hold up to 2 electrons.

• The 3p subshell can hold up to 6 electrons.

• The 3d subshell can hold up to 10 electrons.

Adding these gives a total of ( 2 + 6 + 10 = 18 ) electrons for the third energy level. This understanding aligns well with the construction of the electron cloud and the overall organization of electrons around the nucleus.

When considering the other options, they do not reflect the correct calculation based on quantum mechanics and the capacity of electron shells.